clear;
data=importdata('cdata.txt');
x=data(:,1);
y1=data(:,2);
y2=data(:,3);
[m,~]=size(data);
y=zeros(m,1);
for i=1:m
    y(i)=1.0/(1.0+x(i)*x(i));
end
plot(x,y1,'r')
hold on
plot(x,y2,'b')
plot(x,y,'g')
legend('三次样条结果','二次样条结果','原函数');
